1. Chemical Reactions One or more substances are converted into new substances with different physical and chemical properties. [http://www.hwscience.com/Chemistry/regchemistry/Chemical%20Reactions%20copy.gif]

2. Chemical Reactions Reactants are the substances at the start of a reaction. Products are the substances present at the end of a reaction. [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text _images/CH04/FG04_00CO.JPG]

3. Chemical Reactions Proof of a chemical reaction can be either visible or invisible!!! –Color Change –Temperature Change –Gas Given Off –Light Given Off –Precipitate Formed –Etc…. [http://i.ehow.com/images/GlobalPhoto/Articles/4568652/58345_Full.jpg]

4. Chemical Equations Chemical formulas and symbols used to show reactants and products in a chemical reaction. Example: Sodium metal and Chlorine gas combine to create solid Sodium Chloride

5. Chemical Equations Mass must remain constant in a reaction!!! (# of atoms before and after the “  ”) Use coefficients to balance… 2 2 Na(s)+ Cl 2 (g)  NaCl (s)

6. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter03/Text_Images/FG03_00-03UN1.JPG] Example: H 2 + O 2  H 2 O

7. Chemical Equations Other symbols in the equations…. (s), (l), and (g) stand for solid, liquid, or gaseous states. (aq) stands for aqueous, or dissolved in water.

8. Chemical Equations Example: CH 4 + O 2  CO 2 + H 2 O Begin with elements that appear only in one chemical on both sides of the equation. 2 2

9. Chemical Equations Example: C 4 H 10 + O 2  CO 2 + H 2 O456.52 Double the reaction!!! 81013